Organopolysilane polymers are useful as precursors for the production of silicone carbide fibers. In addition, the polymers are useful as a lithiographic resist material for use in the manufacture of integrated circuits. A fact important to both of these applications is that organopolysilane polymers can become cross-linked when exposed to ultraviolet radiation. However, not all organopolysilanes become cross-linked upon being so irradiated. Instead, some organopolysilanes degrade under UV radiation, without useful cross-linking. In certain applications, the ability to thermally induce cross-linking in organopolysilane polymers would also be useful. For example, the material would have utility as a binder for ceramic composite structures.
Those skilled in the art are cognizant of the use of certain polyvinyl compounds as thermal and radiation-activated cross-linking agents in carbon based polymers. For example, see W. A. Salmon and L. D. Loan, "Radiation Cross-linking of Poly(vinyl Chloride)", Journal of Applied Polymer Science (1972), 16, 671-682. In Salmon and Loan, an electron beam was used for irradiating polyvinyl chloride that had been mixed with such cross-linking agents as n-butyl methacrylate, tetraethylene glycol dimethacrylate, tetraethylene glycol diacrylate, trimethylolpropane trimethacrylate, and trimethylolpropane triacrylate.
The inducement of cross-linking in organopolysilane polymers by use of a polyvinyl compound as a cross-linking agent has not been reported. Likewise, methods have not been reported for inducing such cross-linking in organopolysilane polymers by application of heat or UV radiation in the presence of a polyvinyl compound. Furthermore, the chemistries of carbon-based polymers and organopolysilane polymers are sufficiently different from each other that it cannot be predicted that any particular reaction observed in the one sort of polymer will have an analogue in the other sort. For example, carbon-based polymers typically may be exposed to elemental halogens without degradation of the carbon chain of the polymer. Consequently, reactions may be run involving substituents attached to the carbon chain employing elemental halogens as reactants. In contrast, organopolysilanes undergo scission upon exposure to elemental halogens with the result that corresponding reactions with substituents of the silicon chain cannot be run without disrupting the polymer. Likewise, carbon-based polymers tend to be relatively impervious to ultraviolet radiation, whereas photodegradation occurs readily in many organopolysilanes.